Starting with black outlines. Important thing which could help you paint small details and keep the painted line straight - dip only the tip of the brush in the paint. Not the whole part until the metal. And clean the brush quite often while you paint to remove older, drying paint:

after you are finished with the petals and the flower buds, paint the insides of the flowers in yellow:

Po pomalowaniu wszystkich kwiatow maluje slupki na zolto:

Now it's time to highlight the middle parts (I used too dark fabric, lighter colour would look much better).

I mixed some white and red paint. The important part about highlighting is that it needs several layers of different tones of one colour. This way you can get a nice effect.

What you can do is just mix some paint for the first layer (ex. white and red), for the next layer add more white, and do the same for another layer. You can see on the photo, that the first layer which I painted is not much brighter from the colour of the fabric:

Then I painted the tops of petals with some white/red mix (the colour wasn't the one which I wanted to get, but I didn't buy any pink paint, so it had to be enough) and highlighted the petals with some white lines: